Biaryls, formation heterobiaryls

With the application of copper(I)-thiophene-2-carboxylate (CuTC 76), Liebeskind was able to access substituted biaryls and heterobiaryls at room temperature [73]. The thiophene derivative serves as ligating substituent (Eq. 12.18-1, Scheme 12.18) and mediates the formation of the required aryl copper species. An intramolecular example of such a CuTC-promoted Ullmann reaction in the preparation of tricycle 80 is outlined in Equation 12.18-2, Scheme 12.18. 

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